SockJS

SockJS gives you a coherent, cross-browser, Javascript API which creates a low latency, full duplex, cross-domain communication channel between the browser and the web server. It's websockets for when you can't use websockets (and websockets for when you can, too).

The SockJS family has a JavaScript client for browsers and several server implementations, including JavaScript, Java using vert.x, Python using Tornado, and Erlang as well as some works in progress.

Cloud Foundry

CloudFoundry is an open source Platform as a Service from VMware. What is platform as a service? In short, Cloud Foundry will host your web apps for you, as well as running various servers like MongoDB, Redis and yes, RabbitMQ for you as well. And it's all open source.

VMware runs a free to use instance of Cloud Foundry at CloudFoundry.com; sign up for an account here (but NB we will be giving out promo codes that streamline the process, on Saturday morning).

RabbitMQ

RabbitMQ is a messaging server that gives you a backbone for scaling realtime apps. There are many, many clients for it, for example Node.JS and Ruby. The step-by-step tutorials are a good way to get started, and have code examples for many different languages.